In the prevailing trends in the electronic industry for downsizing appliances, a point of issue is in the relative dimensional accuracy of assembly within an appliance incorporating the components.
For example, in a case where operating portion of a component is standing out from appliance body incorporating the component, it is important to make gap between the operating portion and an aperture of front panel as small as possible from the view point of preciseness of an assembly. On the other hand, however, the gap also plays an important role in absorbing relative dislocation between the panel aperture and the electronic component mounted in the appliance. Therefore, there is a limitation in making the gap small.
A conventional technology is described below using a rotary encoder as an example of the above revolving operation electronic component.
FIG. 5 shows a cross sectional front view of a conventional rotary encoder having push-switch function. The upper part of an operating rod 1 is standing out as an operating section 1A, and a middle column 1B is supported by a round hole 2A of a bearing 2 so that it can make revolving and up-down movements. The operating rod 1 is engaged at a non-round column portion 1C, which is locating lower to the middle column 1B, with a non-round center opening 3A of a revolving member 3 so that the two items revolve together, while the operating rod 1 is allowed to make a free up-down motion independently. A washer 4 is provided at the bottom of the non-round column portion 1C for preventing withdrawal of the operating rod 1.
On the bottom surface of lower flat portion 3B of revolving member 3, a contact board 5 is provided, on which contact board 5 a plurality of line-shaped contact points are disposed in a radial arrangement extending from the center to outside. There are three slider contacts 7A, 7B and 7C popping up from a substrate 6 for keeping an elastic contact with the contact board 5. First terminals 7D, 7E and 7F, connected to respective contact points of the contact board 5, are provided at the outside of bottom part.
There are fixed contact points 8A and 8B in the center of the substrate 6, which fixed contact points are connected to second terminals 8C and 8D provided at the outside of bottom part. Provided above the fixed contact points 8A, 8B is a movable contact plate 9 of domed shape made of a thin metal plate. On the movable contact plate 9, a drive member 10 is provided to form a push-switch. Pushing portion 1D of the operating rod 1 keeps contact with the upper surface of the drive member 10.
The bearing 2 and the substrate 6 are coupled together with a metal frame 11. A mounting foot 11A is provided at the bottom of the metal frame 11 to facilitate its mounting on a circuit board.
In a rotary encoder with push-switch having the above structure, a revolving action given to the operating section 1A of operating rod 1 brings the revolving member 3 to revolve, and the slider contacts 7A, 7B, 7C slide over the surface of contact board 5, which is disposed on the bottom surface of the flat portion 3B. The encoder signals are thus generated.
By a press-down action given on the operating rod 1, the domed movable contact plate 9 contacting to the drive member 10 is reversed to provide electrical contact between the fixed contact points 8A and 8B. Thus, it functions as a push-switch.
FIG. 6 is a cross sectional front view showing the relative relationship between front panel of an appliance and operating knob of a rotary encoder mounted therein. The rotary encoder is mounted on a circuit board 14 of an appliance by inserting the mounting foot 11A, the first terminals 7D, 7E, 7F and the second terminals 8C, 8D coming from substrate 6 into corresponding holes of circuit board to be soldered. An operating knob 12 of column shape is put on the operating section 1A of operating rod 1, and then the circuit board 14 is installed in the appliance so that the operating knob 12 stands out through an aperture 13A of front panel 13.
In the general cases, conventional rotary encoders (the revolving operation electronic components) are first mounted and fixed with solder on a circuit board 14 of appliance, and then the circuit board 14 is installed to a specified place within the appliance. In this case, it is not easy to align the operating knob 12 put on operating rod 1 to the precise location of aperture 13A of front panel 13.
If there is a substantial relative dislocation between the operating knob 12 and the aperture 13A, the operating knob 12 may make contact with the edge of aperture 13A to a blocked functioning, and a comfortable feeling of operation is injured. In order to avoid this to happen, designers of the appliance are compelled to provide a relatively large clearance between the operating knob 12 and the edge of aperture 13A. For compact-size appliances such a large aperture gap is not only conspicuous in the appearance, but it also deteriorates the quality level in the appraisal of products.
The present invention aims to improve the above drawbacks and offer a revolving operation electronic component, as well as an appliance incorporating the component; with which the gap between operating knob and aperture edge can be reduced to a minimum without inviting an inconvenience that results from the relative dislocation between operating knob and front panel aperture.